Electrochemical treatment of saline and alkaline solutions



Aug. 27, 1929.

H. C. PARKER ELECTRO CHEMICAL TREATMENT OF SALINE AND ALKALINE SOLUTIONSFiled Sept. 26, 1928 Patented Aug. 27, 1929.

UNITED STATES HERSCHEL C. PARKER, OF LOS ANGELES', CALIFORNIA.

ELECTROCHEMICAL. TREATMENT OF SALINE AND ALKALINE SOLUTIONS.

Application filed September 26, 1928. Serial No. 308,505.

My invention relates to an electro-chemical treatment of saline andalkaline solutions and apparatus therefor.

In certain lakes brines and alkaline and 6 saline deposits, comprisingmixtures in varying proportions of the chlorides and carbonates ofeither sodium or potassium or both frequently occur. To take a typicalcase of a natural solution, Mono Lake, California,

carries approximately 2 of sodium chlo ride and 2% of sodium carbonatewith very small amounts of other salts. The brine obtained from SearlesLake, California, contains approximately 16% of potassium ch10- ride, 7%borax, 10% of sodium chloride, 8% sodium carbonate, 2% sodium sulphate.It is an object of this invention to subject the solutions justmentioned or similar solutions to an electro-chemical process using 2special electrodes and other conditions so that I obtain as theprincipal products ochre (ferric oxide) and sodium carbonate in a simpleand economic manner.

My process uses iron as the anode, which 2 during the process isconverted to ferrous hydroxide. The ferrous hydroxide because of itstendency to float is decanted from the upper portion of the electrolytewhile the sodium bicarbonate is removed from the anode where itcollects, and because of its greater specific gravity settles at thebottom of the electrolyte whence it may be removed by gravity.

With the above and other objects in view, as which will appear as thedescription pro ceeds, my invention consists of the steps of the processand the apparatus used for carrying out said process hereinafter shownand described.

In the accompanying drawings which form a part of this specification Ihave illustrated the apparatus for carrying out my process, in which:

Figure 1 is a vertical cross section of the apparatus;

Fig. 2 is a sectional view on line 2-2 of Fig. 1;

Fig. 3 is a plan detail view of the anode shown in Fig. 1; Fig. 4 is adetail view of the vibrator;

Fig. 5 is a cross sectional view of the apparatus shown in Fig. 1,illustrating a modified form of the anode;

Fig. 6 is a view similar to Fig. 5, showing 85 still another form ofanode;

Referring to the drawings, 1 indicates an electrolytic cell made ofsuitable material unaffected by the electrolytic process. Verticallydisposed within the cell and preferably in the middle thereof is ananode 2. At opposite ends of the cell 1 and spaced equidistantly fromthe anode 2, are two cathodes 3. The cathodes 3 are connected byconductors 4L and 5 leading to a suitable source of electric energy suchas indicated at 6. A valve controlled inlet pipe 7 conducts the salinesolution to be treated into the cell 1. An overflow pipe 8 leads fromcell 1 to a filter ress (not shown) of any suitable or pre erredconstruction. The anode 2 is made of iron and consists of a plurality ofvertical plates 12 radially arranged and secured to a vertical,non-corrodible shaft 13 such as nickel steel rotated by pulley 14 fromany suitable source of power not shown. A conductor 15 leads from thesource of electric energy 6 to a brush 16 contacting with the shaft 13.The cathodes 3 are made of any suitable material preferably carbon rods3' unaffected by the electrolyte.

A suitable vibrating device; 17 consisting of a toothed wheel 25 fast onshaft 13 and a spring pressed pawl 26, is provided to vibrate the shaft13 and the anode 2 carried thereby, for the purpose of dislodging andshaking off the material collected on said anode. The cell 1 ispreferably provided with the bottom inclined toward the middle asindicated at 1', with a valve controlled outlet 18 arranged just belowthe anode 2.

In place of the anode 2 shown in Fig. 1 a different form illustrated inFig. 5 may be used. The same consists of a container 19 openat thetopand filled with scrapiron 20. The shaft 13 is suitably secured to thebottom of the container 19. The wall of the container 19 is providedwith perforations 19'. The material. used -for making the container is anon-conductor preferably wood or other material unaffected by theelectrolyte.

In Fig. 6 another modification of the anode is illustrated. Here awooden drum 21 mounted on a horizontal shaft 22 and provided with a'door 23 for the insertion of the scrap iron-20 is used, said drum beingprovided with perforations 21'. The horizontal shaft 22 projects throughthe side wall of cell 1 and is driven by a pulley 24'. No vibrator isnecessary in this eonstruc-' tion of the anode, since the tumbling aboutof the scrap iron will dislodge the sodium bicarbonate.

.Assuming that a saline solution containing sodium carbonate and sodiumchloride taken from Mono Lake, California, is to be treated, the same isconveyed into cell 1 and a; current of about 6 volts with a currentstrength of 15 amperes is used. The reactions produced by theelectrolysis are somewhat complicated and are believed to be as follows:

2. Fe+Cl =FeCl 3. FeCl 2NaOH= Fe (OH) 2 2NaCl 4. 2NaOH+ Cl =NaCl NaClO H0 5. Na CO 2H O 2NaOH H CO 3 6. Na CO H 00 2NaHCO The above reactionsare not to be understood to take place consecutively but take placesimultaneously, at least in part, some of them taking place at thecathode and some at the anode. These equations are simply stated to aidin' the explanation as to what most likely takes place in theelectrolytic treatment of the solution.

The sodium chloride will be decomposed into the sodium ions and chlorineions. The sodium ions at the carbon cathodes 3 will decompose the water.forming sodium hydroxide and hydrogen, the latter gas bubbling to thesurface of the electrolyte. The chlorine ions at the iron anode willform sodium chloride and ferrous chloride and the latter reacting withthe sodium hydroxide will form ferrous hydroxide and sodium chloride.Consequently no chlorine will, under the conditions stated, form at theanode and ascend to the surface but will react with the sodium hydroxideand iron.

The chlorine to some extent will also com- & bine with the sodiumhydroxide and form settles to the bottom whence it may be removedthrough the outlet 18. The process may be carried on continuously bycontrolling the inlet 7 and outlets 8 and 18.

The iron hydroxide forms a fiocculent precipitate which rises to the topand is taken out through. the outlet 8. The ferrous hydroxide isrecovered in a filter press and is subsequently dried and converted intoferric oxide by oxidation and forms an excellent pigment suitable forpaints and the like.

The sodium bicarbonate is likewise separated from the liquor in anysuitable manner.

In the saline solutions at Mono Lake and Searles Lake, California, goldin varying quantities is present in soluble form, probably in the formof gold chloride. The gold present in the saline solution subjected tomy treatment, as above described, is reduced to an insoluble form andprecipitated with the ferrous hydroxide from which it may be separatedif present in any paying quantities by any suitable or preferred method.

Various changes may be made by those skilled in the art in'the steps ofthe process or in the construction and arrangement of parts of theapparatus without departing from the spirit of my invention as claimed.

I claim:

'1. An apparatus of the class described comprising a cell having liquidinlets and outlets, an iron anode, a non-corrodible cathode, and meansfor moving the iron anode.

2. An appartaus of the class described comprising a cell having liquidinlets and outlets, an iron anode in the center, and a pair ofnon-corrodible cathodes each equidistantly spaced from the anode.

3. An apparatus of the class described comprising a cell having liquidinlets and outlets, an iron anode in the center, a pair ofnon-corrodible cathodes each equidistantly spaced from the anode, andmeans for vibrating the anode.

4. An apparatus of the class described comprising a cell having liquidinlets and outlets, an iron anode, a rotatable shaft secured thereto,means for rotating said shaft, and a non-corrodible cathode.

5. An apparatus of the class described comprising a cell having liquidinlets and outlets, an anode in the center, said anode comprising arotatable container, a shaft fastened thereto, means for rotating saidshaft, scrap iron in sgid container in contact with said shaft, an apair of non-corrodible cathodes each equidistantly spaced from theanode.

6. A process of treating a solution containing chlorides and carbonatesof the alkaline metals, comprising subjecting said solution toelectrolysis using an iron. anode, whereby iron hydroxide andbicarbonate of the alkaline metal are formed, and separating the ironhydroxide and the alkaline metal bicarbonate from the solution.

7. A process of treating a solution containing sodium chloride andsodium carbonate, comprising subjecting said solution to electrolysisusing aniron anode, whereby 11011 hydroxide and sodium bicarbonate aretion.

8. A process of treating a solution con- 5 taining sodium chloride andsodium carbonate,

comprising subjecting said solution to electrolysis using an electriccurrent of approximately 6 volts and. 15 amperes,

and

using an iron anode, whereby iron hyroxide and sodium bicarbonate areformed, and 10 separating said sodium bicarbonate and iron hydroxidefrom the solution.

In testimony whereof I have signed my name to this specification.

HERSCHEL o. PARKER.

